Tyre treads have a sculptured pattern defined by a plurality of profile elements. Typically, such profile elements comprise circumferential grooves alternated to circumferential ribs, which grooves and ribs extend about the tyre's axis.
Each rib may include a plurality of sub-elements, or blocks, separated by transversal cut edges.
Moreover, each block or rib can have partial cut-outs, or sipes, the radial extension of which stops before the full depth of the block or rib.
The external edges of each sipe may also be defined by, or associated with, a tapered, or chamfered, region.
The number, arrangement and geometry of the aforementioned profile elements, and in particular of the sipes and chamfered regions, influence, and in some cases determine, tyre performances. For example, such profile elements have effect upon wet adherence, braking, cornering and handling properties.
Despite significant investments have been made in the field, and quite a number of tread profile patterns have been proposed over the years, there is still a need for improvement. Such need is particularly felt for passenger (PSR) vehicles, wherein a single tyre tread design must provide a good level of performance in any working circumstance, and especially during braking, cornering and handling, both in wet and dry road conditions.
US 2013/206298 discloses a sculptured tyre tread having a plurality of transverse sipes delimiting respective blocks of a land region. End parts tapering in the longitudinal (circumferential) direction may be provided.
JP 2007-223493 discloses a sculptured tyre tread having longitudinal sipes with end portions tapering longitudinally.